content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * --------------------
   * AbstractDataset.java
   * --------------------
   * (C)opyright 2000-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   Nicolas Brodu (for Astrium and EADS Corporate Research
   *                   Center);
   *
   * Changes (from 21-Aug-2001)
   * --------------------------
   * 21-Aug-2001 : Added standard header. Fixed DOS encoding problem (DG);
   * 18-Sep-2001 : Updated e-mail address in header (DG);
   * 15-Oct-2001 : Moved to new package (com.jrefinery.data.*) (DG);
   * 22-Oct-2001 : Renamed DataSource.java --> Dataset.java etc. (DG);
   * 17-Nov-2001 : Changed constructor from public to protected, created new
   *               AbstractSeriesDataset class and transferred series-related
   *               methods, updated Javadoc comments (DG);
   * 04-Mar-2002 : Updated import statements (DG);
   * 11-Jun-2002 : Updated for change in the event constructor (DG);
   * 07-Aug-2002 : Changed listener list to use
   *               javax.swing.event.EventListenerList (DG);
   * 04-Oct-2002 : Fixed errors reported by Checkstyle (DG);
   * 27-Mar-2003 : Implemented Serializable (DG);
   * 18-Aug-2003 : Implemented Cloneable (DG);
   * 08-Sep-2003 : Serialization fixes (NB);
   * 11-Sep-2003 : Cloning Fixes (NB);
   * 01-Jun-2005 : Added hasListener() method for unit testing (DG);
   *
   */
  
  package org.jfree.data.general;
  
  import java.io.IOException;
  import java.io.InvalidObjectException;
  import java.io.ObjectInputStream;
  import java.io.ObjectInputValidation;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.Arrays;
  import java.util.EventListener;
  import java.util.List;
  
  import javax.swing.event.EventListenerList;
  
  /**
   * An abstract implementation of the {@link Dataset} interface, containing a
   * mechanism for registering change listeners.
   */
  public abstract class AbstractDataset implements Dataset, Cloneable,
          Serializable, ObjectInputValidation {
  
      /** For serialization. */
      private static final long serialVersionUID = 1918768939869230744L;
  
      /** The group that the dataset belongs to. */
      private DatasetGroup group;
  
      /** Storage for registered change listeners. */
      private transient EventListenerList listenerList;
  
      /**
       * Constructs a dataset. By default, the dataset is assigned to its own
       * group.
       */
      protected AbstractDataset() {
          this.group = new DatasetGroup();
          this.listenerList = new EventListenerList();
      }
  
      /**
       * Returns the dataset group for the dataset.
       *
       * @return The group (never <code>null</code>).
       *
       * @see #setGroup(DatasetGroup)
       */
      @Override
      public DatasetGroup getGroup() {
          return this.group;
      }
  
      /**
       * Sets the dataset group for the dataset.
       *
       * @param group  the group (<code>null</code> not permitted).
       *
       * @see #getGroup()
       */
      @Override
      public void setGroup(DatasetGroup group) {
          if (group == null) {
              throw new IllegalArgumentException("Null 'group' argument.");
          }
          this.group = group;
      }
  
      /**
       * Registers an object to receive notification of changes to the dataset.
       *
       * @param listener  the object to register.
       *
       * @see #removeChangeListener(DatasetChangeListener)
       */
      @Override
      public void addChangeListener(DatasetChangeListener listener) {
          this.listenerList.add(DatasetChangeListener.class, listener);
      }
  
      /**
       * Deregisters an object so that it no longer receives notification of
       * changes to the dataset.
       *
       * @param listener  the object to deregister.
       *
       * @see #addChangeListener(DatasetChangeListener)
       */
      @Override
      public void removeChangeListener(DatasetChangeListener listener) {
          this.listenerList.remove(DatasetChangeListener.class, listener);
      }
  
      /**
       * Returns <code>true</code> if the specified object is registered with
       * the dataset as a listener.  Most applications won't need to call this
       * method, it exists mainly for use by unit testing code.
       *
       * @param listener  the listener.
       *
       * @return A boolean.
       *
       * @see #addChangeListener(DatasetChangeListener)
       * @see #removeChangeListener(DatasetChangeListener)
       */
      public boolean hasListener(EventListener listener) {
          List<Object> list = Arrays.asList(this.listenerList.getListenerList());
          return list.contains(listener);
      }
  
      /**
       * Notifies all registered listeners that the dataset has changed.
       *
       * @see #addChangeListener(DatasetChangeListener)
       */
      protected void fireDatasetChanged() {
          notifyListeners(new DatasetChangeEvent(this, this));
      }
  
      /**
       * Notifies all registered listeners that the dataset has changed.
       *
       * @param event  contains information about the event that triggered the
       *               notification.
       *
       * @see #addChangeListener(DatasetChangeListener)
       * @see #removeChangeListener(DatasetChangeListener)
       */
      protected void notifyListeners(DatasetChangeEvent event) {
  
          Object[] listeners = this.listenerList.getListenerList();
          for (int i = listeners.length - 2; i >= 0; i -= 2) {
              if (listeners[i] == DatasetChangeListener.class) {
                  ((DatasetChangeListener) listeners[i + 1]).datasetChanged(
                          event);
              }
          }
  
      }
  
      /**
       * Returns a clone of the dataset. The cloned dataset will NOT include the
       * {@link DatasetChangeListener} references that have been registered with
       * this dataset.
       *
       * @return A clone.
       *
       * @throws CloneNotSupportedException  if the dataset does not support
       *                                     cloning.
       */
      @Override
      public Object clone() throws CloneNotSupportedException {
          AbstractDataset clone = (AbstractDataset) super.clone();
          clone.listenerList = new EventListenerList();
          return clone;
      }
  
      /**
       * Handles serialization.
       *
       * @param stream  the output stream.
       *
       * @throws IOException if there is an I/O problem.
       */
      private void writeObject(ObjectOutputStream stream) throws IOException {
          stream.defaultWriteObject();
      }
  
      /**
       * Restores a serialized object.
       *
       * @param stream  the input stream.
       *
       * @throws IOException if there is an I/O problem.
       * @throws ClassNotFoundException if there is a problem loading a class.
       */
      private void readObject(ObjectInputStream stream)
          throws IOException, ClassNotFoundException {
          stream.defaultReadObject();
          this.listenerList = new EventListenerList();
          stream.registerValidation(this, 10);  // see comments about priority of
                                                // 10 in validateObject()
      }
  
      /**
       * Validates the object. We use this opportunity to call listeners who have
       * registered during the deserialization process, as listeners are not
       * serialized. This method is called by the serialization system after the
       * entire graph is read.
       *
       * This object has registered itself to the system with a priority of 10.
       * Other callbacks may register with a higher priority number to be called
       * before this object, or with a lower priority number to be called after
       * the listeners were notified.
       *
       * All listeners are supposed to have register by now, either in their
       * readObject or validateObject methods. Notify them that this dataset has
       * changed.
       *
       * @exception InvalidObjectException If the object cannot validate itself.
       */
      @Override
      public void validateObject() throws InvalidObjectException {
          fireDatasetChanged();
      }
  
  }
  